As an OCT apparatus which obtains OCT data of a subject, for example, an apparatus capable of acquiring OCT data by processing a spectral interference signal output from an OCT optical system is known, and in recent years, a configuration for obtaining a wide-angle tomographic image by scanning a central portion and a peripheral portion of the fundus in a wide-range has been disclosed (for example, refer to JP-A-2016-209529).
For example, in the apparatus described in JP-A-2016-209529, an optical path length difference of a k clock interferometer provided separately from an OCT interferometer is set to be equal to or greater than 22 mm, and scanning is performed one time in a wide-range of the fundus.
However, in the case of the above-described configuration, it is indispensable to provide the k clock interferometer. Since the k clock requires high-speed sampling, the detector should also have high speed. However, this causes high cost, and further, high frequencies are generally susceptible to noise, and high-speed k clock is likely to lose stability thereof. Therefore, at a depth away from a high-frequency region, that is, a zero delay position, a decrease in SNR and a sampling error due to jitter tend to occur. In addition, when a user tries to stably detect up to high frequencies, the apparatus becomes more complex and extremely expensive.